Preheat the oven to 425°F (220°C).
In a large bowl, toss the halved baby potatoes with 1 tablespoon olive oil, half of the minced garlic, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.
Spread the potatoes evenly on a large rimmed sheet pan. Roast in the oven for 15 minutes.
While the potatoes roast, in the same bowl, combine the sliced red and yellow bell peppers, zucchini rounds, and cherry tomatoes with 2 tablespoons olive oil, remaining minced garlic, lemon zest, lemon juice, dried oregano, smoked paprika, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Toss to coat evenly.
After the potatoes have roasted for 15 minutes, remove the sheet pan from the oven and add the mixed vegetables around the potatoes.
Place the frozen salmon fillets on top of the vegetables, spacing them evenly.
Lightly brush or drizzle a little olive oil over the salmon fillets and season them with a pinch of salt and pepper.
Return the sheet pan to the oven and bake for an additional 10 minutes, or until the salmon is cooked through and flakes easily with a fork, and the vegetables are tender.
Remove from the oven and garnish with chopped fresh parsley before serving.